The Degen lab builds and operates tools for performing magnetic resonance experiments at very small length scales. We are interested in applying these tools for the three-dimensional imaging of single molecules, as well as for the chemical identification of materials with nanometer resolution. We also explore mesoscopic spin dynamics and other fundamental physical phenomena that become important at these small scales.

Magnetic resonance imaging (MRI), well-known from clinical medicine, is in many respects a "perfect" imaging technique: It is truly three-dimensional, chemically specific, works with individual objects and it does not induce any radiation damage in the sample. Unfortunately, MRI is a very insensitive method.  Conventional approaches require sample volumes containing at least one trillion spins to generate a detectable signal, which limits spatial resolution to a few micrometers at best.

In our lab we explore alternative and much more sensitive ways for detecting the same signals from nanometer-sized samples. Using force microscopy, for example, we have recently succeeded in capturing 3D MRI images of single virus particles at about 5 nanometer resolution - a thousand-fold improvement over conventional approaches. Our goal is to apply the same technology for routinely elucidating the 3D structure of a variety of complex biomolecular assemblies, like viruses showing morphology (an example is HIV), molecular machines, or fibrils, and as a general-purpose probe for investigating the chemical composition of a wide variety of materials at the nanometer scale. An important feature of our research is the exploitation of the chemical specificity of MRI, an approach that might permit us to distinguish individual components (like a specific protein) in large assemblies and perhaps even to relate their location to their function.

Our work is currently centered on two experimental approaches. In magnetic resonance force microscopy (MRFM), we use ultra-force-sensitive cantilevers made by lithography to measure small ensembles of spins via their magnetic force. These measurements are done in vacuum and at cryogenic temperatures. In recently-proposed scanning diamond magnetometry, we will combine single spins in diamond with scanning probes to sense minute magnetic signals from samples under ambient conditions.

Our unique "magnetic microscopes" are among the most sensitive in the world, and a substantial portion of the lab's effort focuses on improving our instrumentation. Progress in this area not only enables the study of materials in greater detail, but also permits growth of a deeper understanding of spins microscopic behavior in a new, previously unexplored territory where statistical and quantum effects dominate.  Along the way, we hope to make exciting new physical discoveries.

REPRESENTATIVE PUBLICATIONS

Nanoscale magnetic resonance imaging
C. L. Degen, M. Poggio, C. T. Rettner, H. J. Mamin, and D. Rugar
Proceedings of the National Academy of Sciences U.S.A. 106, 1313 (2009).

Nanoscale magnetometry: Microscopy with single spins
C. L. Degen
Nature Nanotechnology 3, 643 (2008).

One- and two-dimensional NMR spectroscopy with a magnetic resonance force microscope
K. W. Eberhardt, C. L. Degen, A. Hunkeler, and B. H. Meier
Angewandte Chemie International Edition 47, 8961 (2008).

Scanning magnetic field microscope with a diamond single-spin sensor
C. L. Degen
Applied Physics Letters 92, 243111 (2008).

Role of spin noise in the detection of small ensembles of nuclear spins
C. L. Degen, M. Poggio, H. J. Mamin, and D. Rugar
Physical Review Letters 99, 250601 (2007).

Nuclear magnetic resonance imaging with 90-nm resolution
H. J. Mamin, M. Poggio, C. L. Degen, and D. Rugar
Nature Nanotechnology 2, 301 (2007).

Microscale Localized Spectroscopy with a Magnetic Resonance Force Microscope
C. L. Degen, Q. Lin, A. Hunkeler, U. Meier, M. Tomaselli, and B. H. Meier
Physical Review Letters 94, 207601 (2005).